134 NAIL-TAILED WALLABY CHAP. by Banks. It is said that 15 or even 20 feet are covered at a bound, and in bound after bound. But in walking slowly it can be readily seen from an inspection of Kangaroos at the Zoological Society's Gardens that the animal does rest upon its tail, which with the hind-legs forms a tripod. Petrogcde with six species comes next to Macropus, and is indeed only to be differentiated from, it by the thickly-haired and more slender tail, which is not used, as it is sometimes in the Kangaroos, as an extra hind-limb. The Hock-Kangaroos live among rocks, which they climb, and from which they leap ; and the tail acts rather as a balancing pole. The most elaborate account of the anatomy of Petrogale known to me is by Mr. Parsons.1 The dentition as given by Mr. Thomas is I -j- C -g Pm •§• M %—that of Macropus without the occasionally occurring canine of the upper jaw. The osteological characters which separate it from Macropus are quite insignificant. Mr. Parsons mentions a wormian bone, " os epilepticum," at the junction oi the coronal and sagittal sutures. It was found to occur in two out of five skulls examined, and appears not to occur in other Kangaroos. The palatine foramina of Petrogale are so large that the posterior part of the bone is only a narrow thickened ridge. The small intestine of P. xanthopus is 102 inches long, the large intestine 44 inches. The caecum has a length of 6 inches, and is not sacculated, differing in this from the caecum of Macropus major. The best known species are P. wanthopus and P. penicillata. The genus is confined to Australia itself, and does not enter Tasmania. OwycJiogale includes the so-called "Wail-tailed Wallabies,"which have a thorn at the end of the tail, reminding one of the Lion and the Leopard, whose tails have a similar armature. The muffle is hairy. Three species are allowed by Mr. Thomas. Lagorchestes has> like the last genus, the rhinarium, i.e. that part of the nose immediately surrounding the nostrils, hairy instead of smooth as in the Kangaroos proper. It is distinguished from Onychogale by the absence of the terminal callosity to the tail, which is rather short. The name Hare-Kangaroo is given to the members of this genus (three species) on account of their exceeding fleetness. This genus is limited to Australia itself. L. conspicillatus is said to present " a remarkable resem- 1 JVoc. Zaal, Soc. 1890, p. 683.